1. Field of the Invention
The present invention relates to a rotary electric shaver which rotatively drives inner cutters, which are in resilient contact with inner bottom surfaces of circular outer cutters.
2. Description of the Related Art
There has been known a so-called rotary electric shaver which has circular or disk-shaped outer cutters and inner cutter rotating on the inner side of the outer cutters so that beard hair entering the hair introduction slits formed in the outer cutters is cut by the rotating inner cutters. As this type of electric shaver, there has been known in which outer cutter installing holes are formed in an outer cutter frame secured to a shaver main body and circular outer cutters are supported in the outer cutter installing holes such that the outer cutters are slightly movable in a vertical direction and slightly inclinable with respect to the outer cutter frame.
However, the aforesaid construction provides the outer cutters with a limited movable range relative to the outer cutter frame, thus presenting a problem in that the close contact between the outer cutters and skin is restricted with resultant unsatisfactory shaving feeling or inadequate user-friendliness. It has been proposed, therefore, to provide a rim which is movable relative to the main body (the rim being also referred to as an outer cutter rim, an cutter circumferential rim, a skin supporting rim or a skin protecting rim) between the outer cutters and the main body (the outer cutter frame) so as to expand the movable range and the inclinable range of the outer cutters.
JP 9-503424(T) (corresponding to WO 96/02368, U.S. Pat. No. 5,625,950 and EP 0719203) discloses a shaving apparatus which has a skin supporting rim (6) provided between an outer cutter and a main body (an outer cutter frame and a holder 2). The outer cutter is held by the rim such that it is slightly movable in a vertical direction and also slightly inclinable, and the outer periphery of the rim is pivotally supported by the outer cutter frame of the main body. More specifically, the rim enters a circular opening of the outer cutter frame, and a pair of projections provided on the outer periphery of the rim is engaged with the inner peripheral surface of the opening provided in the outer cutter frame. In other words, a pivotal supporting section is disposed between the outer periphery of the rim and the opening of the outer cutter frame. Further, adjoining rims are hinge-connected (e.g., by a tongue-and-groove joint). It has been required, therefore, to form the linear joint of the adjoining rims. In addition, the restoring force of an inclined rim has been imparted by an upward force of an inner cutter drive shaft or the force of restoration (the force for restoring from an inclination) of an inner cutter drive shaft to the upright position thereof.
JP 2007-151925(A) (corresponding to US 2007-124936 (A1)) discloses a shaving apparatus in which the upper surface of a shaver main body (a head bottom plate) is provided with an upright wall (a supporting section 54) surrounding a cutter circumferential rim (cutter frame 18) holding an outer cutter, and each cutter circumferential rim is independently and pivotally retained to the upright wall. In other words, the upper surface of the shaver main body (the head bottom plate) is exposed between the cutter circumferential rims.
JP 2007-117190(A) (corresponding to US 2007-089298(A1) and EP 1779983A1) discloses a shaving apparatuses in which a cutter unit (16) consisting of an assembly of an outer cutter and an inner cutter is pivotally retained in an outer cutter mounting aperture (20) formed in an outer cutter frame (18), which is openable/closable or detachable relative to a shaver main body.
JP 2007-319339(A) (corresponding to US 2007-277379(A1) and EP 1862271A1) discloses a shaving apparatus in which an outer cutter frame (20) fixed to a shaver main body is provided with an outer cutter mounting hole (22) for mounting each cutter unit (18), a slit (50) extending toward the center of the shaver main body from an outer periphery is formed between adjoining outer cutter mounting hole (22), and a portion surrounding each of outer cutters (14) partitioned by the slit (50) is inclinable or bendable.
According to the shaving apparatus disclosed in JP 9-503424(T) (corresponding to WO 96/02368, U.S. Pat. No. 5,625,950, and EP 0719203), the adjoining cutter circumferential rims (the skin supporting rims) are hinge-connected, so that the joint portion is linear, thus restricting the shapes or placements of the cutter circumferential rims.
Further, pressing or depressing one cutter circumferential rim against the skin and inclining the cutter circumferential rim on the skin causes all cutter circumferential rims to be interlockingly pressed and tilted, resulting in an increase in a pressing force (depressing start pressure or an inclination start pressure) of each cutter circumferential rim. The pressing force or the inclining start pressure is set by an upward force or a force of an inner cutter drive shaft to restore from an inclination. The contact pressure applied by the inner cutter to the outer cutter cannot be set excessively low; otherwise, the performance for shaving beard or shaving feeling would be deteriorated. For this reason, it is difficult to set the pressing force of the cutter circumferential rims to an adequately small value.
Further, according to the shaving apparatus disclosed in JP 9-503424(T) (corresponding to WO 96/02368, U.S. Pat. No. 5,625,950, and EP 0719203), the outer cutter and the rim are reset to their stationary positions by the force of the inner cutter drive shaft to restore to an upright position. Since the inner cutter drive shaft is normally vertical, the outer cutter will normally restore to a horizontal position. This presents a problem in that the inclination of the outer cutter at the stationary position cannot be arbitrarily set. There is another problem in that the inclinable range of the cutter circumferential rim is restricted.
According to the shaving apparatus disclosed in JP 2007-151925(A) (corresponding to US 2007-124936(A1)), the upright wall of the upper surface of the shaver main body is exposed between adjoining cutter circumferential rims. This causes a problem such that the head assembly becomes inevitably larger, and shaving debris or beard trimmings easily adhere to the upper surface of the shaver main body, making it difficult to remove the debris.
The shaving apparatus disclosed in JP 2007-117190(A) (corresponding to US 2007-089298(A1) and EP 1779983A1) presents a problem in that the outer cutter frame surrounding a plurality of cutter units inevitably becomes large, resulting in a large head unit. The one disclosed in JP 2007-319339(A) (corresponding to US 2007-277379(A1) and EP 1862271A1) has a drawback in that the cutter unit tilts (or bends) together with the portion partitioned by the slit of the outer cutter frame, thus restricting the movement of the outer cutter and also preventing easy cleaning.